/**
 * Copyright 2018 Nikita Koksharov
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.redisson.rx;

import org.reactivestreams.Publisher;
import org.redisson.api.RFuture;
import org.redisson.api.RListAsync;

import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.FutureListener;
import io.reactivex.functions.LongConsumer;
import io.reactivex.processors.ReplayProcessor;

/**
 * Distributed and concurrent implementation of {@link java.util.List}
 *
 * @author Nikita Koksharov
 *
 * @param <V> the type of elements held in this collection
 */
public class RedissonListRx<V> {

    private final RListAsync<V> instance;

    public RedissonListRx(RListAsync<V> instance) {
        this.instance = instance;
    }

    public Publisher<V> descendingIterator() {
        return iterator(-1, false);
    }

    public Publisher<V> iterator() {
        return iterator(0, true);
    }

    public Publisher<V> descendingIterator(int startIndex) {
        return iterator(startIndex, false);
    }

    public Publisher<V> iterator(int startIndex) {
        return iterator(startIndex, true);
    }

    private Publisher<V> iterator(final int startIndex, final boolean forward) {
        final ReplayProcessor<V> p = ReplayProcessor.create();
        return p.doOnRequest(new LongConsumer() {

            private int currentIndex = startIndex;
            
            @Override
            public void accept(final long n) throws Exception {
                instance.getAsync(currentIndex).addListener(new FutureListener<V>() {
                    @Override
                    public void operationComplete(Future<V> future) throws Exception {
                        if (!future.isSuccess()) {
                            p.onError(future.cause());
                            return;
                        }
                        
                        V value = future.getNow();
                        if (value != null) {
                            p.onNext(value);
                            if (forward) {
                                currentIndex++;
                            } else {
                                currentIndex--;
                            }
                        }
                        
                        if (value == null) {
                            p.onComplete();
                            return;
                        }
                        if (n-1 == 0) {
                            return;
                        }
                        accept(n-1);
                    }
                });
            }
        });
    }
    
    public Publisher<Boolean> addAll(Publisher<? extends V> c) {
        return new PublisherAdder<V>() {

            @Override
            public RFuture<Boolean> add(Object o) {
                return instance.addAsync((V)o);
            }

        }.addAll(c);
    }

}
